Crucible.



G. N. JBPPSON.

GRUGIBLE.

APLIcATIoN FILED AUG.7,1911.

g Patented Dec. i6, 3913.

ing so completely protected as to prevent all im iran sauras earner ortica QEOBGE JEPPSON, OF WORCESTER, MASSACHUSETTS, ASSIGNOR T0 NORTON COMPANY, OF WORCESTER, MASSACHUSETTS, A CORPORATION' OFMASSA- CHUSEITS.

CRUCIBLE.

Application filed August 7,

T0 all whom 25 may concern.'

Be it known that I, GEORGE N. JnrPsoN, a citizen of the United States, residing at Worcester, in the county of' lWorcester and State of Massachusetts, have invented certain new andi` useful Improvements in Crucibles, of whilth the following is a specification.l

rIhis invention relates to filtering crucibles, filtering or porous dishes, tubes, disks or plates, extraction thimbles, or similar articles, the object of the invention being. to provide articles of this character constructed with glazed and unglazed portions or areas, the glazed portion or portions bepenetration of liquids into the interior thereof.

Heretoforc porous tubes and vessels have been partly glazed by dipping or coating, with subsequent firing, but such articles have proven useless for certain purposes re quiring complete impenetrability to liquids of the glazed area, as for example in the case of articles intended for quantitative chemical work. "Ihe reason for this is that the glaze, particularly when of a refractory character, does not as a rule completely penetrate the wall, but leaves a porous interior layer, into which liquids or suspended materials may freely penetrate and from which it is almost impossible to remove them. Accordis to the present invention the glazed portion is so completely isolated from the unglazed portion as to prevent such penetration, thus making the article suitable for use as a filter or the like for quantitative work.

For a full understanding of the invention, reference is made to the accompanying drawings wherein:

Figure l is a central vertical section of a crucible which has been partially glazed by the methodsv heretofore used; Fig. 2 is a similarview illustrating one step of my method, the upper and lower portions of a porous crucible being shown in separated relation; Fig. 3 is a similar view of a completed crucible in accordance with this invention; Fig. i is a similar viewof an eX'- traotion thimble the upper portion of which has been glazed according to this invention; and Fig. 5 is a detail on a larger scale.

In said drawings, lthe crucible illustrated in Fig. l comprises a porous body Specification of Letters Patent. Fatah-ted U99. 1913.

1911. serial No. 642,830.

portion l, to the upper portion .of which is applied a glaze 2, which may as indicated at 3 partially penetrate the body, leaving however an interior porous layer t, into which liquids or fine suspensions may pass freely by capi-llarity, but from which they cannot be removed by washing. In order to prevent such penetration it is necessary either that the interstices beneath the glaze shall be completely filled, which is practicable only with very thin walled, crucibles and comparatively fluid or highl7 penetrating glazes; or that an impervious septum or .layershould be provided between the glazed and unglazed areas. According to the present invention, the latter course is adopted. Toaccomplish the desired result I may proceed as follows: The previously formed porous body of the crucible or other vessel or article is first cut, as by a diamond saw or other suitable implement, along the line of demarcation between the part to be glazed and that which is to remain porous. Thus in Fig. 2, the porous body 1 has been cut into upperand lower sections la and l". The sect-ion 1a may now be glazed by any approved method, being'completely covered by the glazing composition; the lower or cut edge in particular should be sufficiently coated to form an effective impervious septum or impenetrable layer, as indicated at 5 in Figs. 3' and 4f. While the composition is yet sufliciently plastic, the two portions of the crucible are reunited under light pressure, and the whole is then fired in the usual manner. The resulting article presents glazed areas which are completely impenetrable to liquids, owing to the presence of the above described septum and the complete filling of the voids or interstices of this portion' of the wall.

The invention is particularly advantageously applied to articles formed of previously molten alumina.

While I have described as a preferred embodiment of my invent-ion a method wherein the article is first formed as a whole,.then cut, and one or more of the separated p0rtions glazed before reassembling, it should be understood that in some ca'sesit is pracL ticable to mold or otherwise form the parts of the completel article separately, thea to" glaze such of these partsA as are to be rendered impervious, andI finally to assemble the article as herein described; Thus in the extraction tllimble represented in Fig. 4, the l 2. As a new article of manufacture, a upper orv glazed portion la is in form a porous container having glazed marginal simple cylinder which may readily be sepaportions, said glazed portions isolated from rately molded for attachment to the porous the unglazed portions by a septum of glaz- 15 5 body portion lb. ing composition.

l claim: In testimony whereof, I ailix my signature l. As a new article of manufacture, a in presence of tWo Witnesses. porous Crucible or' other article having j GEQRGE N. JEPPSON. glazed and unglazed portions, said glazed Nitnessesz 10 portions isolated from the unglazed por- PERCY A. BoEoK, vtions: by a septum of glazing composition. HARRY A. NOYEs. 

